Professor Noel Sharkey of the University of Sheffield, in an address given to a defense-oriented think tank in London, pointed out that combat robots, or "autonomous weapons systems," were already being used by several countries.

"The trouble is that we can't really put the genie back in the bottle," he said in a press release before his speech to the Royal United Services Institute. "Once the new weapons are out there, they will be fairly easy to copy. How long is it going to be before the terrorists get in on the act?"